FET-based planar circuits for quasi-optical sources and transceivers

The circuits that are simple in construction and exhibit isotropic conversion gain are discussed. Both single-device and balanced transmitter and transceiver circuits are described. Balanced sources are presented that can be operated in push-pull mode for frequency doubling. A single-FET quasi-optical oscillator circuit using a microstrip patch linear array and having an effective radiated power of 31.6 dBm at 10 GHz is reported. A dual-FET frequency-doubling oscillator circuit using a coupled rampart line antenna with an effective radiated power of 21.6 dBm at 19.7 GHz is also described. Quasi-optical transceiver elements are presented that use the FETs as both signal sources and self-oscillating mixers for down-conversion of the received signal. The application of these transceiver elements to Doppler motion detection is reported.<
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